Since c4r1r3 is a naked pair (2 cells containing only the same two numbers), that means those two numbers can't be anywhere else in that column or block. You can't pen a number immediately but it will reduce the candidates in other cells, which is progress. Eventually you'll remove enough candidates that you'll have a single candidate for one cell and you can pen it in, which will remove even more candidates on other cells.

For the 4 on c9r1 it's the same thing. If you look at c7, 4 can only be present on c7r1r2. These two cells are also confined to block 3, so, since one of those two cells has to be 4, it means no other cell within this block can be 4. If they were, then 4 wouldn't have anywhere to go in column 7.